From another place!

[pgb]

Over on the WNXX forum somebody posted this which occurred last night - or rather early this morning by the looks of it.

"Our train got stuck west of Hyde Park Corner this am and after limping into the platform, found this;

rjhamilton.fotopic.net/p63572144.html

OOI, does anyone know LU's policy on cancelling the last train of the day - do passengers get taxis home or get pushed onto the night buses (there's one from Trafalgar Square to Cockfosters and another to Heathrow T5). I didn't hang around to find out"

Looked quite an interesting chain of events - any idea what happened?

[21146]

Seems a track bolt became wedged between point blades ar Hyde Park Corner and caused a signal failure, delay 50 minutes.

[londonstuff]

For signals associated with points, do the points have to fully lock in place before the signal clears so that there's no risk of derailment if the points only half clear because of an obstruction?

[Deleted]

The points have to be locked and (more importantly) proven locked before the signal will clear.

Someone else will no doubt be along to fill in the details!!!

[mrfs42]

I don't think there's any more details to fill in - it obviously varies between locations and for what purpose the points have been called, but you've quoted the basics.

<PNCLCR, PNCLCSR, QNCLCR, QNCLCSR or others> ;D

[railtechnician]

Interesting in that there is little detail given here, presumably the points in question were one end of 17s trailing crossover. HPC used to be part of my maintenance area and I can certainly recall changing a chairlock unit on the 'B' end and a motor on the 'A' a few years ago which reminds me that both ends were/are chairlocks. Chairlock switches are locked normal and reverse as appropriate and only unlocked to traverse N-R or R-N so presumably a previous train had been reversed and one of the switches had been fouled by the track bolt as the points were normalised.
Obviously points do have to be set appropriately and locked before a route over them can be cleared so almost any obstruction will foul the lock, the switch only requiring to be held off the stock rail by 5/32" to indicate failure.
50 minutes delay seems long but one must appreciate that the nearest depots these days are Ash House, Arnos Grove and Earls Court Control Room. In the old days a King's Cross lineman would have been called but the depot was closed some years ago as it was becoming difficult to cover all depots with several vacancies in the roster at each. It is unlikely that the Earl's Court lineman would have attended (no transport kept there!). I suspect the Acton Town lineman would've attended by road and then West End traffic comes into play!